merc 115 blueband help please....!

[iainstevenson]

I am fairly new to boating and also this website, must say what a great site before i go any further.
Recently bought a 17ft speedboat with a 115 blueband mercury on it. On the test run it was fine, on the second run out it overheated and jammed. having spoken to the mechanic in the shop he thinks the impeller is likely to have gone and the engine heat seized as it turned over after about an hour of cooling down. The mechanic has told me that he couldnt change the impeller because he couldnt get the gear box off without causing damage and suggested a new engine. On getting the boat home i decided to see if i could do any better. I managed to undo the six nuts holding the gearbox on and the whole thing dropped out quite easily without any forcing or undue pressure. I now have a gearbox on the garage floor with the drive shaft poking out the top. Should the drive shaft have come out with it and where would the impeller be? sorry for being so long winded but would love to avoid the cost of a new engine.
ps i have no reason for not trusting the mechanic as he seemed to be completely honest and forthright from the start and also didnt cost the earth!

 

[rickdb1boat]

Re: merc 115 blueband help please....!

You should see the water pump housing right on top of the lower unit. Driveshaft goes right through it. Under it is the impeller. You're past the hard part. Replacing the pump is a piece of cake...

Sorta like this:

 

[iainstevenson]

Re: merc 115 blueband help please....!

your a gentleman, many thanks
Any other pointers would be gratefully received.


cheers

 

[Chris1956]

Re: merc 115 blueband help please....!

Ian, First check the compression of the 6 cylinders. If you have zero on number 3 or number 1(which is likely after an overheat), you will need to repair this first.:'(

You will also need to get yourself a manual to do the waterpump job.

 

[denny4]

Re: merc 115 blueband help please....!

I just went thru something similar, now i need to do a rebuild....no compression in my #4 and others down 10%:'(. Hopefully you can save yours, goodluck.

 

[SeaKaye12]

Re: merc 115 blueband help please....!

Mighty interesting that the wrench said that he couldn't get the lower unit off; eh???...yet it dropped right down for you...

There's not many jobs that are easier to do than dropping the lower unit on one of those...unless sometimes salt water corrosion does it's thing on the bolts and can often cause the driveshaft to stay frozen (by corrosion) at the spline up at the top where it enters the powerhead.

Does your engine show evidence of a lot of corrosion? It's hard to imagine what caused your mechanic to say that...

When it comes time to re-assemble the thing...pay attention to the shift-shaft splines.....that's the only thing that caused me a bit of grief when I did mine...I had to drop the thing again...put the MerControl in FWD...Put the Lower unit in FWD...and try again....

Let us know if your engine survived...

Thanks for reading, Chuck

 

[tashasdaddy]

Re: merc 115 blueband help please....!

pay attention on whichway the vanes on the impeller are leaning. so you get the new one in correctly.

 

[Texasmark]

Re: merc 115 blueband help please....!

Also insure that you put the key in the impeller so it is locked to the shaft.

A little vaseline or soapy water, with a second set of hands helps too.

Expect the pump to be eccentric. That's how it compresses water and develops pressure.

On reinstalling, be sure that the water tube coming from the pump sticks in the hole in the bottom of the power head. That's how you get water up there.

Insure that the gearshift is lined up. Easiest way is to move your shift lever back and forth and find center. Then move the shift shaft (on the lower unit) back and forth finding center, then join her up.

Do not force R gear; spin the prop slowly when going into R.

If the splines don't line up you can do a trial and error or wrap a string around the shaft and pull the string, or reach in with a pair of long nose pliers.

Mark

 

[emckelvy]

Re: merc 115 blueband help please....!

Something sounds Fishy with that mechanic, Methinks he was trying to take you for a ride!

 

[soulfish]

Re: merc 115 blueband help please....!

You should see the water pump housing right on top of the lower unit. Driveshaft goes right through it. Under it is the impeller. You're past the hard part. Replacing the pump is a piece of cake...

Sorta like this:

Maybe I can get some help for my problem here? I have a 115 1998 offshore. I had the lower rebuilt, after a gear broke.
(after a dealer/service visit where they told me that they had pressure and vacuum tested and refilled the unit, that's another story)
After the rebuild, had some water in the lube, took back to have resealed, still getting water. I am assuming I got hosed and they never resealed the top.
I want to do this myself if possible. Nothing leaking around the prop shaft. Noticed after having the motor tilted up for a week, a couple drops of the fresh lube (boat hasn't been wet this year yet) running down from the water pickup holes/slots. Would this indicate lube leaking through the top shaft seal or somehow coming through the pump, or both? Steer me towards help if possible. Thanks.